Sampling apparatus

ABSTRACT

An apparatus for use in sampling material on-line in a process system, comprising a sample collector ( 1 ) for receiving a sample of material, an elongate shaft ( 10 ) defining a passageway ( 14 ) carrying a measurement probe ( 11 ) for taking measurements from a colelcted sample, a pressurised fluid supply ( 31 ) connected to the passageway for delivering a pressurised fluid through the passageway to the sample collector for displacing the collected sample and a nozzle ( 33 ) provided at the distal end of the measurement probe ( 11 ) for distributing the pressurised fluid to the sample collector for displacing the collected sample from the sample collector ( 1 ).

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an apparatus for sampling material in aprocess system, in particular the on-line sampling of a flow of a liquidor powder.

BACKGROUND OF THE INVENTION

Traditionally, a sample of material would have been removed duringprocessing from a process system and then analysed. It will beappreciated that techniques requiring the removal of material from aprocess system for separate analysis are both labour-intensive and timeconsuming.

More recently, techniques have been developed which allow material to beanalysed on-line. One such device is disclosed in WO 99/32872. Thisdocument discloses a device for use in and a method of sampling materialon-line in a process system which comprises a sample collector in whichin use a sample of material is collected and a measuring device fortaking measurements from the collected sample. The device furthercomprises a sample displacing means for displacing the collected samplefrom the sample collector so that the sample collector can receive a newsample of material. The sample displacing means comprises a pressurisedgas supply, which in use is actuated to displace the collected sampleand a small bore tube for leading the pressurised gas from the pressuregas source to the sample collector.

Ordinarily, this device has been found to operate satisfactorily.However, occasionally, it has been found that the sample collector isnot completely emptied before receiving a new sample. Materialproperties of the sample, like binding forces can make it difficult tobreak up the sample and empty the sample collector. In some cases,sample particles have a sticky surface and tend to stick to each otheror to the surface of the sample collector. It will be appreciated thateven small residues of the previous sample in the sample-collector areundesirable as they might influence the measurement on the next sample.

Another sampling apparatus is known from U.S. Pat. No. 5,750,996. Inthis document an apparatus and method for non-destructive inspection ofa coated article is described. The apparatus comprises a probe, whichhas a recess for receiving coated article and a communicating fiberopticreceiving passageway. To displace the coated article from the recess,pressurised air is supplied to the lower portion of the recess tothereby urge the coated article out of the recess.

A drawback with the device described in U.S. Pat. No. 5,750,996 is thatit is difficult to completely empty the recess of coated article. Afurther drawback is that the outlet for pressurised air might getclogged as particles fall down into the outlet due to its position inthe bottom of the recess.

SUMMARY OF THE INVENTION

A general object of the present invention is to solve or alleviate theproblems described above.

It is thus a general aim of the present invention to provide anapparatus for and a method of periodically sampling material on-linewhich is capable of consistently producing samples which arerepresentative of the entire bulk of material from which samples aretaken.

It is a particular aim of the present invention to provide a samplingapparatus which allows material to be sampled and replaced with newmaterial in a quick and efficient manner.

A further aim of the present invention is to provide a samplingapparatus which ensures a stable interface between the material to besampled and the measuring device. Where a flow of material is to besampled, it is desirable to present a stationary sample to the measuringdevice.

Accordingly, the present invention provides an apparatus for use insampling material on-line in a process system, comprising a samplecollector for receiving a sample of material, an elongate shaft defininga passageway carrying a measurement probe for taking measurements from acollected sample, a pressurised fluid supply connected to the passagewayfor delivering a pressurised fluid through the passageway to the samplecollector for displacing the collected sample, and a nozzle provided atthe distal end of the measurement probe for distributing the pressurisedfluid to the sample collector for displacing the collected sample fromthe sample collector.

In preferred embodiments the process system in which the samplingapparatus is used is a process vessel or a tubular section, such astubes leading to or from a process vessel or bulk container.

The construction allows for a collected sample from which measurementshave been taken to be replaced both simply and rapidly. The reliabilityin the measurements is increased as the sample collector is efficientlyemptied before receiving a new sample. In addition, the configuration ofthe sampling apparatus of the present invention is such that it is ineffect self-cleaning, thereby minimising the downtime of the processsystem from which material is being sampled. Moreover, the samplingapparatus of the present invention allows for the use of any kind ofmeasuring device which utilises electromagnetic radiation.

In use the pressurised fluid supply is actuated to provide pressurisedfluid to the passageway of the shaft and the nozzle through which thepressurised fluid is distributed to the sample collector to displace thecollected sample. The nozzle according to the present inventiondecreases the risk of clogging of the displacing means, increases thenumber of points of action and creates a reliable functionality of thesampling apparatus.

Preferably, the nozzle is substantially ring-shaped and mounted over thedistal end of the measurement probe.

Preferably, the nozzle is provided with at least one angled, spiralgroove through which the pressurised fluid is distributed. In this way aturbulent and focused stream of fluid is provided to the samplecollector. The angle, the size, the geometry and the number of spiralgrooves all work together in creating a well defined swirl of thepressurised fluid that empties the sample collector by pneumatictransport.

Preferably, the open-topped chamber comprises an arcuate wall member onwhich a sample is in use collected and front wall member which is flaredoutwardly and upwardly.

In one embodiment the measuring device is a spectroscopic measuringdevice and can be a reflectance, transflectance or transmission device.Preferably, the spectroscopic measuring device is one of an emission,absorption or scattering device. In preferred embodiments thespectroscopic measuring device is an x-ray spectrophotometer, anultra-violet (UV) spectrophotometer, a visible (VIS) spectrophotometer,an infra-red (IR) spectrophotometer, a near infra-red (NIR)spectrophotometer, a raman spectrophotometer, a microwavespectrophotometer or a nuclear magnetic resonance (NMR)spectrophotometer.

In another embodiment the measuring device is a polarimeter.

In a preferred embodiment the measuring device includes a measurementprobe to be introduced into the passageway of an elongate shaft and thesample collector is attached to the distal end of the shaft. Preferably,the sample collector is releasably connected to the shaft by means of abayonet fixing. In this way the sample collector may be easilydisconnected from the shaft and the parts subject to cleaning. Inanother embodiment the sampling apparatus is made in one piece.Preferably, the sampling apparatus is slidably mounted through anaperture in the wall of the process vessel such as to be movable withinthe process system. This configuration is particularly useful whenrepresentative samples are not to be found adjacent the wall of aprocess system or if homogeneity is to be monitored at differentlocations within a process system.

Preferably, the elongate shaft is provided with an aperture throughwhich pressurised fluid is introduced for displacement of a sample. In apreferred embodiment the pressurised fluid is a gas, for examplepressurised air. In another embodiment, the pressurised fluid is acleaning fluid that is introduced through the aperture in the shaft whenthe apparatus is subject to a cleaning procedure. Cleaning in place(CIP) is particular useful when cleaning the sampling apparatus betweenbatches as the sample apparatus does not need to be removed and/or takenapart. In a still further embodiment, the fluid is a process fluid, thatis a fluid used in the process carried out in the process system, i.e. acoating fluid.

In a preferred embodiment the sample collector is connected to aheating/cooling means so as to provide for temperature stabilisation ofthe sample collector. Temperature stabilisation can provide morereliable measurements where the measuring device is sensitive tovariations in temperature or where, for example, the material to besampled is a liquid which tends to boil and the gas bubbles generatedadversely affect the measurement.

In another embodiment, at least one sensor is provided in the samplecollector. For example, the sensor is a temperature sensor or a pressuresensor.

The present invention finds particular application in monitoring thecharacteristics of a sample of material, for example compositionalchanges, of pharmaceutical compositions typically in the form ofpowders, granules, pellets and tablets during preparation in fluidisedbeds. However, it will be appreciated that the present invention canequally be applied to other processes within the pharmaceuticalindustry, and indeed in non-pharmaceutical processes. Other processes towhich the present invention can be applied are typically blendersystems, powder transport devices, spray granulators, spray dryers andmixing/separation systems.

Preferred embodiments of the present invention will now be describedhereinbelow by way of example only with reference to the accompanyingdrawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a sampling apparatus in accordance witha first embodiment of the present invention incorporated in a processvessel.

FIG. 2 illustrates a front view of the sampling apparatus of FIG. 1.

FIG. 3 illustrates an exploded view of the sampling apparatus of FIG. 1.

FIG. 4 a illustrates a front view of the nozzle member of the samplingapparatus.

FIG. 4 b illustrates a sectional view of the nozzle member of thesampling apparatus.

FIG. 5 a schematically illustrates a sectional view of the samplingapparatus according to a second embodiment.

FIG. 5 b schematically illustrates a sectional view of the samplingapparatus according to a third embodiment.

FIG. 6 illustrates a flow chart of a method of sampling material inaccordance with the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1-3 illustrate a sampling apparatus in accordance with a preferredembodiment of the present invention.

The sampling apparatus comprises a sample collector 1 for collecting asample of material, a measuring device 3 for taking measurements from acollected sample, a sample displacement means comprising a pressurisedfluid supply 31 and a nozzle 33 for distributing the supplied fluid, fordisplacing a collected sample and a controller 6. The operation of eachof the sample collector 1, the measuring device 3 and the pressurisedfluid supply is performed under the control of the controller 6,typically a computer or a programmable logic controller (PLC), as willbe described in more detail hereinbelow.

The measuring device 3 includes a measurement probe 11, in thisembodiment a near infra-red reflectance probe, which extends through theperipheral wall 7 a of a process vessel 7 such that the distal end 13 ofthe measurement probe 11, through which radiation is emitted andreceived, is directed into the sample collector 1. In this mannermeasurements can be taken from a sample of material collected in thesample collector 1. The measurement probe 11 is introduced into theelongate shaft 10 connected to the sample collector 1.

The measuring device 3 further includes a radiation generating unit 15for generating electromagnetic radiation and a detector unit 17 fordetecting the radiation diffusely reflected by a collected sample.

In this embodiment the radiation generating unit 15 comprises in thefollowing order a radiation source 19, preferably a broad spectrumvisible to infra-red source, such as a tungsten-halogen lamp, whichemits radiation in the near infra-red interval of from 400 to 2500 nm, afocusing lens 21, a filter arrangement 23 and at least one fibre cable25 for leading the focused and filtered radiation to distal end 13 ofthe measurement probe 11. In this embodiment the filter arrangement 23comprises a plurality of filters, each allowing the passage of radiationof a respective single frequency or frequency band. In other embodimentsa monochromator or a spectrometer of Fourier transform kind can be usedinstead of the filter arrangement 23.

In this embodiment the detector unit 17 comprises in the following orderan array of fibre cables 27, whose distal ends are arranged around thedistal end of the at least one fibre cable 25 which supplies radiationto a collected sample, and a detector 29 connected to the fibre cables27. The detector 29 is preferably an array detector such as a CMOS chip,a CCD chip or a focal plane array. The distal ends of the fibre cables27 are preferably spaced from the distal end of the at least one fibrecable 25 in order to minimise the effect of specular reflection or strayenergy reaching the fibre cables 27. In use, the detector 29 willproduce signals S depending upon the composition of the sampled materialand the frequency of the supplied radiation. These signals S are thenamplified, filtered and digitised so as to be available for furtherprocessing. The processed signals can be used to perform real-time orsubsequent analysis. Alternatively or additionally, the processedsignals can be used for process control.

The sample collector 1 connected to an elongate shaft 10 is preferablyslidably mounted through the peripheral wall 7 a of a process vessel 7.In this way, the sample collector 1 can be positioned at a range ofpositions relative to the wall 7 a of the process vessel 7 so as toallow measurements to be taken from samples at those positions. However,if desired, the sampling apparatus may be fixed in relation to the wall7 a at a desired position for receiving samples from a certain positionin the process system.

In a preferred embodiment, the sample collector 1 defines an open-toppedchamber comprising an arcuate wall member S on which in use powder iscollected and a front wall member 9 which tapers upwardly and outwardlyfor assisting in guiding material thereinto. The arcuate wall member 8defines the bottom and the sides of the open-topped chamber in thesample collector 1. Due to the arcuate shape, the emptying of theopen-topped chamber is facilitated. No obstructing sharp edges arepresent that could hinder the sample leaving the sample collector. Theupwardly and outwardly flared front wall 9 will further facilitate theemptying of the sample collector 1. Since the angle of the front wall inrelation to the bottom is greater than 90 degrees, the sample can easilyexit the sample collector 1 when hit by the stream of fluid from thenozzle 33.

An additional advantage of the outwardly and upwardly flared front wall9 is that any light passing through the sample to the front wall will bereflected away instead of reflected back to the measuring device 3.Light that is reflected back to the measuring device from the front wallmight disturb the measurement of the sample.

Preferably, the sample collector 1 and the elongate shaft 10 are made astwo separate parts and connected before being introduced into a processvessel or the like. However, the sample collector and the elongate shaftmay as well be made in one piece.

In another embodiment schematically illustrated in FIG. 5 a the samplecollector 1 consists of the open topped chamber, comprising the arcuatewall member 8 and the front wall member 9, and a portion of the distalend of the elongated shaft 10. This is achieved by not introducing themeasurement probe all the way through the elongate shaft. In this waythe collected sample is protected in the sample collector during themeasurement while a part of the elongate shaft 10 serves as a roof overthe sample-received in the chamber. This embodiment is particularlyuseful if a sample is to be taken in a process system with turbulentconditions.

In a further embodiment schematically illustrated in FIG. 5 b the samplecollector 1 is defined in a portion of the distal end of the elongatedshaft 10. In this embodiment the elongate shaft 10 is angled against theperipheral wall 7 a such that bottom of the sample collector isrepresented by the distal end 13 of the measurement probe 11. Anadvantage of this embodiment is the close contact between the sample andmeasurement probe as the sample falls upon the distal end 13 of themeasurement probe.

FIGS. 4 a and 4 b illustrate the nozzle 33 for distributing thepressurised fluid to the sample collector 1. The nozzle is substantiallyring-shaped with a rim 38 around its outer periphery except for asmaller flat portion 39. The nozzle is held in place inside the elongateshaft 10 by the rim 38. The flat portion 39 prevents the nozzle fromrotating when it is mounted in the elongate shaft 10. Preferably, thenozzle 33 is provided with one or more grooves 35 on its inner surfaceserving as outlets through which the pressurised liquid reaches thesample collector 1. Most preferably, the nozzle is provided with two tofour grooves. However, the exact number and size of the grooves 35depend on the particle size of the sample to be displaced. If theparticle size of the sample is rather small the nozzle 33 tends to haveseveral smaller grooves and on the other hand, if the particle size ofthe sample is large the nozzle should preferably have less but broadergrooves. The groove 35 it self is angled in order to improve theturbulent flow creating a swirl to empty the sample collector.Preferably, the nozzle 33 is moulded from a dielectric plasticsmaterial. However, the nozzle 33 can also be made from a metal such asaluminium or stainless steel.

After a measurement has been performed, the sample is displaced by usinga high-pressure fluid source 31, which in a preferred embodiment is anair compressor. The fluid source is connected to the elongate shaft 10through an aperture 12 in the wall of the shaft. The aperture ispreferably located in the proximal end of the elongated shaft 10.Pressurised fluid is provided to the nozzle 33 via the passageway 14 ofthe elongate shaft 10. The nozzle 33 is mounted over the measurementprobe 11 and the probe is introduced into the elongate shaft. An edgecut out in the distal end of the elongate shaft will hold it in place.When high pressure fluid, in a preferred embodiment pressurised air,reaches the nozzle 33, the fluid is forced through at least one spiralgroove 35 in the nozzle 33 whereby a turbulent flow, a whirl, is createdin the sample collector 1 such that the sample is removed from thesample collector. Typically, the pressurised fluid is at a pressure ofthe order 1 bar and is supplied for about 0.1 seconds. The pressure andthe duration of the pressure pulse which has to be used will varydepending upon the material being sampled.

The sequence of operation of the sampling apparatus 2 is schematicallyillustrated in FIG. 6. In use, a sample is first collected in the samplecollector 1 (Step 1). The sampling apparatus is then initiated to startmeasurement either automatically or by the intervention of an operator(Step 2). Under the control of the controller 6, measurements are thentaken from the sample collected in the sample collector 1 using themeasuring device 3 to generate data corresponding to the receivedradiation (Step 3). As the data is generated it is then either analysedin real time or stored for subsequent analysis (Step 4), with theresulting information optionally being used for process control. Afterall of the required measurements have been taken from the sample, thecontroller 6 then actuates the sample displacement device which in thisembodiment actuates the high-pressure fluid source 31, whereuponpressurised gas is delivered through the space 14 to the nozzle 33 intothe sample collector 1 and the sample resident in the sample collector 1is displaced such that a new sample can be collected (Step 5). Thesampling method can then be repeated to take measurements from anothersample of material.

Finally, it will be understood by a person skilled in the art that thepresent invention is not limited to the described embodiments but can bemodified in many different ways without departing from the scope of theinvention as defined in the appended claims.

1-26. (canceled)
 27. An apparatus for use in sampling material on-linein a process system, comprising: a sample collector for receiving asample of material; a measurement probe for taking measurements of thecollected sample in the sample collector, wherein the measurement probehas a proximal and distal end; an elongate shaft having a passageway forcarrying the measurement probe, wherein the elongate shaft has aproximal and distal end; and a pressurized fluid supply for delivering apressurized fluid through the passageway to the sample collector fordisplacing the collected sample from the sample collector.
 28. Theapparatus according to claim 27, wherein the measurement probe is a partof a spectroscopic measuring device.
 29. The apparatus according toclaim 28, wherein the spectroscopic measuring device is one of areflectance, transflectance or transmission device.
 30. The apparatusaccording to claim 27, further comprising a nozzle provided at thedistal end of the measurement probe for distributing the pressurizedfluid to the sample collector.
 31. The apparatus according to claim 30,wherein the nozzle is provided with at least one spiral groove on theinner surface through which groove the pressurized fluid is distributed.32. The apparatus according to claim 31, wherein the at least one spiralgroove is angled to improve turbulence in the flow of the pressurizedfluid.
 33. A process system comprising the apparatus according to claim27, wherein the sample collector is located within the process system.34. An apparatus for use in sampling material on-line in a processsystem, comprising: a sample collector for receiving a sample ofmaterial; a measurement probe for taking measurements of the collectedsample in the sample collector, wherein the measurement probe has aproximal and distal end; an elongate shaft having a passageway forcarrying the measurement probe, wherein the elongate shaft has aproximal and distal end; a pressurized fluid supply for delivering apressurized fluid to the sample collector for displacing the collectedsample; and a nozzle comprising at least two outlets for distributingthe pressurized fluid to the sample collector for displacing thecollected sample from the sample collector
 35. The apparatus accordingto claim 34, wherein the nozzle is provided at the distal end of themeasurement probe.
 36. The apparatus according to claim 34, wherein thenozzle is provided with at least one spiral groove on the inner surfacethrough which groove the pressurized fluid is distributed.
 37. Theapparatus according to claim 36, wherein the spiral groove is angled toimprove turbulence in the flow of the pressurized fluid.
 38. Theapparatus according to claim 34, wherein the pressurized fluid supply isconnected to the passageway and delivers the pressurized fluid throughthe passageway to the sample collector.
 39. The apparatus according toclaim 34, wherein the measurement probe is a part of a spectroscopicmeasuring device.
 40. The apparatus according to claim 39, wherein thespectroscopic measuring device is one of a reflectance, transflectance,or transmission device.
 41. A process system comprising the apparatusaccording to claim 34, wherein the sample collector is located withinthe process system.
 42. A method for sampling material on-line in aprocess system, comprising: receiving a sample of material in a samplecollector, taking measurements of the collected sample in the samplecollector by means of a measurement probe; and delivering a pressurizedfluid coaxially along the length of the measurement probe to the samplecollector for displacing the collected sample from the sample collector.43. The method according to claim 42, wherein the pressurized fluid isdistributed at several points of action to the sample collector.
 44. Amethod for sampling material on-line in a process system, comprising:receiving a sample of material in a sample collector; takingmeasurements of the collected sample in the sample collector by means ofa measurement probe; delivering a pressurized fluid to the samplecollector at several points of action to displace the collected samplefrom the sample collector.
 45. The method according to claim 44, whereinthe pressurized fluid is delivered coaxially along the length of themeasurement probe.